I agree with Fisherman's and the old JW premise. Unlike Jewishness, which is matriarchal, Sin appears to be Patriarchal.
Jesus according to the legend, had to be a Jew. Thus he had to be born of a Jewish mother.
IF, as the legend tells us, Jesus was Perfect, it must have been because he did not inherit imperfection from his Mother or his father. Since Jesus' mother was a human female with inherited sin, Jesus' father must have been the source of his Perfection.